This invention relates generally to a clutch release assembly for selectively coupling a clutch between an engine and a transmission of a motor vehicle.
Clutches for motor vehicles typically include a sleeve connected to a release bearing actuated by a clutch lever or fork. The sleeve engages clutch springs or levers that bias a clutch plate into engagement with a flywheel driven by the engine. The sleeve slides axially along and rotates with an input shaft of the transmission. A clutch release beating is disposed on the input shaft to engage the sleeve and transmit axial movement from the clutch fork. Typically, the clutch release bearing includes an inner race that rotates with the input shaft and the sleeve, and an outer housing or race that remains stationary relative to the inner race. Typically, the outer housing includes wear pads that are in contact with the clutch fork. The clutch fork is pivotally mounted to a housing and pivoted by an actuator in response to an operator depressing a clutch pedal. The clutch fork pivots to move the clutch release bearing axially along the shaft and thereby open the clutch.
The pivotal motion of the clutch fork in combination with frictional force between the fork arms and wear pads creates an uplift force on the clutch release bearing and sleeve. The uplift force is approximately equal to the coefficient of friction between the fork arms and the pads multiplied by the normal force applied to the arms against the pads. The uplift force presses the sleeve against the input shaft during clutch disengagements to accelerate wear of the shaft and clutch release bearing.
For this reason it would be desirable to design a clutch release bearing and fork actuation assembly that could further increase the life of the bearing sleeve by eliminating friction that induces uplift and accelerates wear.